Asymmetric split H-shape nanoantennas for molecular sensing

Abstract

In this paper we report on a very sensitive biosensor based on gold asymmetric nanoantennas that are capable of enhancing the molecular resonances of C-H bonds. The nanoantennas are arranged as arrays of asymmetric-split H-shape (ASH) structures, tuned to produce plasmonic resonances with reflectance double peaks within the mid-infrared vibrational resonances of C-H bonds for the assay of deposited films of the molecule 17β-estradiol (E2), used as an analyte. Measurements and numerical simulations of the reflectance spectra have enabled an estimated enhancement factor on the order of 105 to be obtained for a thin film of E2 on the ASH array. A high sensitivity value of 2335 nm/RIU was achieved, together with a figure of merit of approximately 8. Our experimental results were corroborated using numerical simulations for the C-H stretch vibrational resonances from the analyte, superimposed on the plasmonic resonances of the ASH nanoantennas.

Frontiers of light manipulation in natural, metallic, and dielectric nanostructures

“…In addition, square fractal-like nanoapertures in a gold film have been considered; they show an EF 10 3 and a refractive index sensitivity of more than 2 × 10 3 nm/RIU [253]. The combined effect of NAs sharp edges and nanoslit hot-spots has been adopted using an asymmetric H-shaped splitted nanoantennas array, in detecting M concentrations of 17-Estradiol molecules [254]. The sharp edges of NAs and the narrow slit between them allows to achieve high EF ( 10 5 ) and good sensitivity, up to 10 3 nm/RIU, but the asymmetry of the structure induces some limitation in SEIRA analysis.…”

Biomedical Optical Sensing Using Nano-/Micro-Structured Metamaterials

“…Reasonably typical metasurfaces are produced as uniform arrays of individual metallic film patterns, e.g. split-ring resonators (SRRs) and asymmetric split-ring resonators (ASRRs) [3][4][5][6][7], FRAMMs [8] (Fano-resonant asymmetric metamaterials) and split-H structures (ASHs) [9,10], on dielectric substrates. Such dielectric substrates should, of course, be transparent at the operating wavelength, for situations where the observation is based on resonant changes (e.g.…”

“…One emphasis in our presentation will be on the use of ASH structures [9,10] for bio-sensing -applied to hormones that are of interest in both biomedicine and in the environment. Recent work on estradiol, an important hormone for human health and animal welfare, will be reviewed.…”

Array metasurfaces for biomedical sensing at infra-red wavelengths

“…silica glass) substrates. A variety of elementary structures have been described in the literature -including asymmetric split H-shaped (ASH) structures [1], single-gap split-ring resonator (SRR) structures [2,3] and double-gap asymmetric split-ring resonator (ASRR) structures [4][5][6]. ASH structures are of particular interest because of their ability to operate effectively in orthogonal polarisation situations.…”